Apparatus for directing air to combustion products turbines



Oct 6, 1953 G. K. w. BoEsTAD. Erm. 2,654,220

f APPARATUS FOR DIRECTING AIR To coMBUsTIoN PRODUCTS TURBINES Original Filed Dec. 1, 1945 4 Sheets-Sheet 1 /p /2 22 /ff G. K. W. BOESTAD ET AL APPARATUS FOR DIRECTING AIR TO Oct. 6, 1953 2,654,220

coMBUsTIoN PRODUCTS TURBINES 1, 1943 4 Sheets-Sheet 2 Original Filed Dec.

lv 5.6, l

Oct. 6, 1953 G. K. w. Bol-:STAD ET Al. 2,654,220

` APPARATUS FOR DIRECTING AIR TO COMBUST'ION PRODUCTS TURBINES l, 1943 4 Sheets-Sheet 5 Original Filed Dec.

Oct. 6, 1953 G. K. w. BOESTAD ET AL 2,654,220

APPARATUS FOR DIRECTING AIR To COMBUSTION PRODUCTS TURBINES Original Filed Dec. l, 1943 4 ShetS-Sheet 4 03 j 62. 0/ y; 93% WM /00 K/ 94 /05 'a 73 u U /05/ f ments will thus become sealed against the surroundings. The turbine discs l2 are provided with axial channels 22 which are disposed alternately on different radii and connect the various spaces 253 with each other.

The discs l2 of the rotor carry blades 24 which are arranged, together with stationary guide blades 2t secured in the turbine housing, in a passage 35 having the gaseous working medium iiowing therethrough. The outermost turbine disc I2 on the left hand side in Fig. 1 (the high pressure side of the turbine) may, over a preferably conical portion 32, be made integral with a shaft 34 cooperating in known manner with radial and axial thrust bearings 315 secured in the turbine housing. Arranged between the portion 32 and the shaft 3 are packing members 3B, 38 on both sides of the bearing 35. The outermost disc I2 on the opposite side of the rotor is con-- nected to a shaft 4t mounted in bearing 42. A

medium of the gas turbine plant, such as the air which is compressed by a compressor contained in the gas turbine plant, may be conveyed through a socket i5 to an annular chamber 48 in the housing 28 and thence through channels 50 as well as through channels 5l in the iirst guide blade rim 26 at the high pressure end of the turbine to channels 52 opening into a chamber 5K5 at the left hand of the disc I2 in the drawings. From the chamber 5t, the cooling air flows through the channels 22 to the spaces 20 in the rotor, a relative rotary movement being set up between the cooling air and the walls of the turbine disc, so that high coenicients of heat transfer are obtained. The cooling air then enters the channel l, which is closed on both sides, and continues through a radial channel 5E in the iirst turbine disc l2 at the high pressure end of the rotor, whereupon the cooling air is introduced into the space 58 behind the iirst guide blade 26 and is carried along with the current of driving medium flowing through the passage 3b. The space 58 is separated from the chamber '54 by means of packings 6U.

The cooling air is taken oi at such a point on or behind the compressor that when entering somewhat higher than the pressure in the space 58.

The rotor Il) may be made from steel of the martensitic or some equivalent type. On the other hand, the blades 24 are made from austenitic or sorne equivalent steel having a high heat resistivity. The latter steel at the same time has a coeihcient of heat expansion about 50% greater and a less heat conductivity than martensitic steels. Thus, the rotor proper as well as the turbine housing may be constructed from a cheaper steel having a good heat conductivity and a small coeicient of expanasion, which results in the disadvantages of different expansions of the rotor and the housing upon changes in temperature being reduced to a great extent. The blades occupy a comparatively small portion of the radial extension of the turbine, by reason of which a greater heat expansion on the part of the blades is of little import. The turbine housing 28 is preferably made from a material having a coefficient of heat expansion of the same magnitude as that of the rotor material. Furthermore, the housing 28 may be protected against the hot working medium by means of rings 21 from austentitic or some equivalent steel, in which the guide blades 25 are secured. Provided in the inlet passage of the turbine is a partition or reduce clearances.

jacket 3| having a cooling agent owing theren about on the outside.

The embodiment according to Fig. 3 diiers from the preceding one substantially only in that the rotor l0 is made with an integral blade-carrying part. This part is provided with channels 62 for the cooling air extending axially therethrough, said channels being located outside the average radius of the rotor as near to the points of attachment of the blades 24 as possible. The channels E2 are not through-passages at the right hand end of the rotor l0 in the drawing, but communicate through radial channels 64 with the central channel I4. The cooling air is conveyed from the space 48 to the chamber 54 through passages G6, 58 in reinforcing members 'Hl located in front of the rst guide blade and in the housing 28.

The gas turbine plant illustrated in Fig. 4 comprises a compressor 'l2 which is driven by the gas turbine 14, the blade-carrying rotor lil of which may form an integral part as in the embodiment according to Fig. 3. The air compressed in the compressor flows through a conduit 'i5 to a heat exchanger 80 arranged in the outlet conduit 78 from the turbine, and further through a conduit 82 to a combustion chamber 64 into which the fuel is introduced through a nozzle Sii. Disposed in the combustion chamber 84 is a partition or cooling jacket 3l in which the hot working medium flows. The space around the cooling jacket 3l is traversed by comparatively cold air adapted to cool the wall of the combustion chamber and the turbine housing, said air then entering the blade system together with the hot Working medium. Through a pipe 88, cooling air is supplied to the annular chamber i8 in the turbine housing. From this chamber, the cooling air may then be introduced into the space between the jackets 3l and 84, or may be conveyed to the blade system. Through a conduit 89, 9i extending from the conduit 82, cooling air is conveyed to the chamber 54 and thence through the channels B2, lli, 5E to the rear side of the rst guide blade rim 26 in the turbine. A conduit extending from the conduit 'I6 may be connected with the conduits 89, 9|, .a three-way valve 93 being inserted therebetween so that the cooling air may be taken from either the conduit 82 alone or from said conduit and the conduit 16. The air coming from the conduit 82 is warmer than that from the conduit T6, and by this arrangement the setting up of stresses in the rotor material by too great differences of temperature in its various parts is avoided. In this guide blade rim, the drop of heat may be so great, without any detrimental effect, that a suicient drop of pressure is obtained to keep a sufcient quantity of air in circulation through the cooling passages of the rotor in normal operation.

It is advantageous to form the turbine in such manner that the rotor may be heated up more slowly than the housing, so that expansion of the latter in advance of the former during starting or warm-up periods will enlarge rather than When the turbine is cut on, the opposite will then be the case, in that the rotor will cool down more slowly, whereby the clearances between the turbine blades and the housing are reduced and the sealing edges between the latter may be worn to greater clearances in normal operation of the turbine. To obviate disadvantages of this kind, there is provided a valve 92 in the conduit 'i6 behind the the kinetic energy of the rotating masses, the -A rotor is kept running for a while, and the rotation may be maintained for a longer time with the aid of the starting motor 9d, if required. In this way, an enicient cooling of the rotor may be had also when the rotation is slow.

In the embodiment according to Fig. 5, 'I2 designates a low pressure compressor and 96 a high pressure compressor, the conduit between them having an air cooler 98 arranged therein. 'i4 denotes the low pressure turbine driving the compressor, and |09 designates the high pressure turbine driving the compressor 96. The air compressed in the compressor 96 to its nnal pressure ows through the conduit 18, the heat exchanger 89 and the combustion chamber 9d to the gas turbine and from the latter to a combustion chamber |02, into which the fuel is introduced through a nozzle |04 to reheat the working medium, before the same enters the turbine 74. The turbine lli also drives a generator (not shown), for example. In both turbines, the rotor is provided with a system of cooling passages according to the invention.

Extending from the conduit S2 and preferably also from the conduit I5 are conduits |03 and |95, respectively, which by the three-Way valve 93 are connected to a conduit |98. Cooling air is supplied through said conduits and a branch conduit |08 to the rotor of the high pressure turbine |09.' The conduit |06 communicates with a conduit II2 extending from the outlet |0I of the high pressure turbine to the cooling system of the 10W pressure turbine, as well asv with a conduit |07 opening into the chamber 54 of the low pressure turbine. The conduit |01 may have a cooler ||0 connected into the same. Provided between the conduits |06, |01 and II2 is a three-way valve IM adapted to cut off the conduit |96 in normal operation, when cooling medium passes through the conduits I I2, |97 and through the cooler IIB to the low pressure turbine. When the gas turbine plant is put out of operation, the valve ||4 is shifted simultaneously with the closing of the valve 92, so that cooling air Will now pass through the conduits |98 and |07 to the low pressure turbine. The valve 93 then also takes a position to allow a flow of air through the conduits |05 and |06. Thus, powerful cooling of both rotors will be obtained.

Novel features of turbine structure per se not claimed herein form the claimed subject matter of our aforesaid U. S. Patent No. 2,487,514.

While dilerent modifications of gas turbine systems have been shown herein by way of illustration, it is to be understood that the scope of the invention is not to be limited thereby but is to be determined by the scope of the appended claims.

What we claim:

1. A gas turbine system comprising an elastic iluid gas turbine, said turbine comprising stator and rotor structures providing between them a channel for expansion of gaseous motive uid,

compressor means for compressing a gaseous constituent of said motive uid, said rotor being provided with interior passages for W of a gaseous cooling medium through the rotor, said passages having outlet means opening into said channel at a place spaced from the inlet end of the channel where the pressure cf the motive iluid expanding in the channel is less than the pressure thereof at the inlet to the channel, main conduit means having heating means therein and connecting the discharge side of said compressor means with said inlet of the channel, secondary conduit means connecting the discharge side of said compressor means with said cooling passages for flow of a portion of the compressed gaseous medium through the rotor and discharge of substantially all of said portion through said outlet means to said channel for expansion therein with the motive fluid admitted through said inlet, and valve means for selectively controlling the flow or fluid from said compressor means through said secondary conduit.

2. A system as defined in claim l, in which said valve means comprises a valve in said main conduit behind the inlet of said secondary conduit considered in the direction of flow of fluid through the main conduit.

3. A system as defined in claim l, including a by-pass conduit and regulating means therein for Icy-passing a selected quantity of fluid. heated by at least a portion of said heating means from said main conduit to said secondary conduit to control the temperature of the fluid admitted to said cooling passages.

4. A system as defined in claim 3, including valve means for controlling the relative pressures and amounts of fluid delivered from the main conduit and the by-pass conduit to said secondary conduit, whereby to regulate the temperature `and amount of fluid delivered to said cooling passages.

5. In a gas turbine system, a turbine having a bladed rotor providing cooling passages for cooling the blade carrying structure of the rotor, air compressing means for compressing air to be used as a constituent of the motive uid for the turbine, conduit means including a combustion chamber connecting said compressor means with said turbine for supplying hot products of combustion as motive huid thereto and additional conduit means including an air heater separate from said turbine and from said combustion chamber and valve means for supplying to said cooling passages a controlled portion at regulated temperature of the air delivered by said compressor means.

GUSTAV KARL WILLIAM BOESTAD. ERIK OTTO ERIKSSON.

References Cited in the le of this patent UNITED STATES PATENTS Number Name Date 1,960,810 Gordon May 29, 1934 2,243,467 Jendrassik May 27, 1941 2,353,929 Ray July 18, 1944 2,479,777 Price Aug. 23, 1949 2,489,683 Stalker Nov. 29, 1949 FOREIGN PATENTS Number Country v Date 542,528 France May 18, 1922 471,051 Germany Feb. 6, 1929 

